Heartbeat network for a two-node active-passive cluster

We have two network connection between the two clustered nodes(each node has two NIC's). One is for the local area network (public) and the other one is for the heartbeat, and we have two switches to handle these two network. Since we have a two-node cluster, we are using the 'Node and Disk Majority' for the quorum. The idea of the node and disk majority is that Nodes and witness disk can vote in case something goes wrong. Say if I unplug the network connection for the heartbeat network, how do the nodes and witness disk to communicate to vote since the heartbeat network is down? are they using the public network or there is some internal clustering process handling the voting without the need of heartbeat network?
wingman

Thank for the reply.
The reason I asked the question is because when I unplugged the heartbeat network cable, no failover occurs. On the public network, I do allow cluster to use it as well. Does this mean the cluster use the public network to detect the heartbeat? Or is it because the Disk and Node Majority voting system still thinks the active node is up because of more than half of the voting party ( each node plus a designated disk) still available?
Wingman

Hi,
The fact that you (rigthly) configure cluster traffic on the public network as well prevents the cluster from going into a "split brain" situation. However, your Node and Disk Majority configuration makes it possible for the cluster to be up as long as one of your nodes and the Witness disk are up and voting so it would handle the "split brain" situation anyway.
/Elisabeth